cost of subterranean parking

[Martin Z.]

Hello Everyone, in part of a potential multifamily development, I want to get a ball park figure on subterranean parking for 3 or possible 4 levels down on approp. 18,500 SF. of land.  project is in the LA area.  Does the cost per level decrease as the number of levels increase?  it would be part of a mix used project and I need the parking to get the building done so i have no other choice other than to dig down.

thank you in advance